Tag Archives: August

Arid and sunny

August raw anomaly data (orange)

In August 2017 all moisture indicators except rainfall showed even greater aridity (high up on the graphs) than in July. Daily minimum temperature anomaly (lower left graph) fell extremely low, but both the daily maximum temperature anomaly (x-axis in all graphs) and that of subsoil (lower right graph) were just slightly above normal.

Fully smoothed data (red)

Fully-smoothed data points now include summer 2016-17. The daily maximum temperature anomaly peaked in February 2017 at +0.9°, much the same temperature as in the previous two peaks: February 2016 and October 2014. The daily minimum temperature anomaly was just about to peak, but the subsoil temperature anomaly was rising persistently.

Moisture anomaly variables, which had moved strongly towards arid in the spring, peaked in aridity during the summer:

Lowest rainfall, in January, was just 13 mm below normal;
least cloudiness, in February, was still 11% above normal;
lowest dew point, in November, was 1.7° below normal;
widest daily temperature range, in January, was only 0.1° wider than normal.

Although aridity reached peaks, this was not an arid summer. The peak values cited were not far from normal, and the graphs show that more arid times occurred within the previous two years.

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

* Normal values for rainfall are based on averages for the 125 years beginning 1883.

Six days with at least eight millimetres of rain made for a very wet August.
On the average, the temperature was normal until the fourth week, which was cool. However, there were two remarkably cold days. The 3rd, at 10.6°, was the second coldest August day and the 22nd, at 11.6°, the fifth coldest. Most nights were cool, around 1°, but several were much warmer, generally with the rain. Most days were sunny, and eighteen of the mornings were frosty, about three more than usual.

Comparing August months

On average, the days were cold: as cold as in August 2001, but not as cold as in 2008 or 2010. The average night-time temperature, however, was normal. The dew point, while not high, was higher than in the previous four August months.
The monthly rainfall total of 80.2 mm was twice the average (40 mm), and in the 89th percentile. No rainfall total for any number of months is now below the 19th percentile. That is the 42-month total of 1949 mm, which is a mere 313 mm lower than the median 42-month value. Both Greenhatch Creek and Rushes Creek have flowed in recent weeks.

Data. Rainfall figures for this month are from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

August raw anomaly data (orange)

August 2016 was marked by low mean daily maximum temperature and high total rainfall. On the first graph the data point is in the cold wet “flooding rains” corner. However, the other five variables are close to normal.

Fully smoothed data (red)

Fully-smoothed data is now available for the summer of 2015-16. Most variables became static in that season, but cloudiness increased, dew point fell, and subsoil temperature rose.
Most variables were close to normal: rainfall, cloudiness, daily temperature range and subsoil temperature. Daily maximum and minimum temperatures were rather high, while dew point was low. [Low dew point anomalies near the line (y = -x – 3) rather than (y = -x) may be due to an instrument error, since corrected.]

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

* Normal values for rainfall are based on averages for the 125 years beginning 1883.

Up to the 24th of August, there had been no rainfall readings above 6 mm for 67 days, and none at all for 29 days. Then storms brought 34 mm one day and 4 mm the next. A little more fell on the 28th. Overcast skies came with the rain, and one morning had fog until after 9 am.
Two days were unusually cool: the 5th was 6° below normal and the 27th was 7° below normal. By contrast, the minimum temperature on the warm rainy morning of the 24th (13.5°) was 9.4° above normal. There were 15 frosts (normal), but the coldest morning, the 5th, reached only minus 2.1°.
The weekly average temperature was a little low in the sunny first half of the month. It was high just before and during the rain, then low again.

Comparing August months

This month was close to normal, and very like August last year.
Days were a bit cool. That made the daily temperature range rather low, in line with rather cloudy skies.
The rainfall of 40.1 mm was on average, and in the 57th percentile. As happened last month, only one rainfall total was as low as the 9th percentile. That serious shortage had now moved back to the 30-month total (1255 mm). Water is flowing in Greenhatch Creek.

Data. All data, including subsoil at 750 mm, are from 3 Monash Street, Manilla. Rainfall data up to 26/3/15 is from Manilla Post Office, Station 055031.

Fully smoothed data (red)

The last fully-smoothed data point (February 2015) completes the summer of 2014-15. This summer had a steady cooling and moistening trend for all variables except subsoil temperature, which passed through a minimum. Three of these seven variables were very close to normal: daily maximum temperature, rainfall, and subsoil temperature. Skies were rather cloudy, dew point was three degrees low (as is now usual), daily temperature range was half a degree low, and daily minimum temperature was half a degree high. These four variables all relate to moisture. Only the dew point shows low moisture: the others show high moisture, while the rainfall was normal.

August raw anomaly data (orange)

The partially-smoothed data points from March to July (uncoloured) show excursions, but the unsmoothed data point for August (orange) is close to the trend established in the summer. That is, cooler and moister. However, no variables had values far from normal.

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

* Normal values for rainfall are based on averages for the 125 years beginning 1883.

Parametric plots of smoothed climate variables at Manilla
“August 2014 back to normal”

August data (orange)

Most raw anomaly values for August have returned to near normal. The daily maximum temperature anomaly has finally fallen below normal and rainfall has risen above normal. The dew point anomaly remains well below normal, but its value is on the (green) trend line that has applied during the last three years.

Fully smoothed data (red)

Fully-smoothed data is now available for the summer season ending in February 2014. During the summer all variables except daily minimum temperature moved decisively away from drought. Rainfall increased rather slowly, but cloudiness increased very rapidly, and daily temperature range fell very rapidly.

The hot-arid climatic peak (drought) of spring 2013

Extreme anomaly values of climate variables came in the following order:

This is not the order that is typical in recent extreme episodes. The smoothed rainfall anomaly minimum of -22.3 mm (not nearly as low as the -27.1 mm of July 2002) came much later than the peak of daily maximum temperature. On the top left graph the trace curved anti-clockwise, which is unusual.

Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999. They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

The daily weather log

Early-blooming Hardenbergia

The weekly temperature was normal throughout, but the first half of the month had sunny warm days, cold nights and very dry air. The night of the 3rd (-4.0°) was the coldest August night this century, and the early morning of the 12th had the lowest August dew point (-8.7°). Two brief overcast and rainy spells began on the 16th and 26th, yielding 54.4 mm in five rain days. The reading of 26.6 mm on the 17th was one of the highest for August in recent years.
The number of frosts (12) was a little below normal (15).

Comparing August months

While August 2008 had been the coolest, and August 2009 the warmest in the 21st century, nearly all averages this month were near normal. As exceptions, the daily maximum temperature was slightly low and the dew point (as in the two previous August months) was very low. Few mornings had dew on the grass.
The total rainfall of 54.4 mm is in the 75th percentile, well above the August average (40 mm). This rain also raised the rainfall totals for periods of more than one month, so that only the 18-month total of 691 mm now remains as a serious shortage (9th percentile).

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

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Back-dated monthly reports

Monthly and seasonal weather reports for Manilla now extend back more than nine years to June 2007. [Select ARCHIVES for the month following.]
"Manilla 3-year climate trends" graphs and reports extend back to May 2010 as consecutive months. Earlier graphs and reports are accessed in ARCHIVES September 2002, 2004, 2006, and 2008.